New here. Great site.

New plugs and coil packs installed two years ago. It is shaking upon acceleration and idle. Has lost a lot of power. I can floor it and it won't go over 70 MPH. Where do I start looking? It is not giving any codes.

 

Are you using Resistor style spark plugs? Sometines they fail and then will become delayed in their spark rate. Often seen in shifting with an auto transmission as shuddering and loping.

 

maybe the cat. converter is almost clogged up and causing too much back pressure ! if you changed the plugs 2 yrs. ago it might be time to change them again if you put a lot of miles on them ! did you check the motor mounts ? you might have 1 busted !